The present invention relates to a selector mechanism for an infinitely variable belt-drive automatic transmission for a vehicle, and particularly to a mechanism for performing the selection of operational ranges of the automatic transmission.
U.S. Pat. No. 4,304,150 discloses an infinitely variable transmission for a vehicle. The transmission comprises an endless belt running over a driving pulley and a driven pulley, each pulley is so designed that the running diameter of the driving belt on the pulley varies by a hydraulic control system. In the system, operational ranges such as a drive range (D), reverse range (R), neutral range (N), and parking range (P) for locking the output shaft of the transmission during parking of the vehicle are provided. In addition, it has proposed to provide a high engine speed drive range (Ds range) in which the transmission is downshifted. Accordingly, in the Ds range, the vehicle is driven in a high engine speed range, which enables sporty driving and active uphill/downhill driving. The selection of these ranges is performed by manipulating a selector lever. It is preferable that the selection is performed by shifting the selector lever along a straight line.
The transmission is so arranged that the D-range is selected by selecting gears in a selector device. On the other hand, the Ds-range is obtained by changing the state of a hydraulic control circuit without changing a D-range gear train. Accordingly, a selector mechanism for selecting the Ds-range must be provided with a mechanism for holding the D-range. In order to meet these requirements, the selector mechanism is apt to be complicated, if a conventional change speed mechanism such as shifter rails and shifter arms is employed.